HR: 08:30h
AN: C41C-03    [Abstracts]
TI: Neogene Tectonic Events in the Marie Byrd Land Sector of the West Antarctic Rift System: Their Potential Impact on Ice Sheet Evolution and Stability.
AU: * Le Masurier, W E
EM: wesley.lemasurier@colorado.edu
AF: Institute of Arctic and Alpine Research (INSTAAR), University of Colorado, Boulder, CO 80309-0450, United States
AB: The West Antarctic rift system is buried beneath 1-4 km of ice over much of its extent, obscuring vast areas that could provide clues about the potential for active volcanism beneath the ice sheet, and whether significant tectonic movement has taken place in Cenozoic time. This study explores the consequences of viewing the ice as basin fill, and of approximating the mass equivalent of ice as unconsolidated sediment. It then compares the results with active rift systems elsewhere in the world. The results suggest (1) that the interior rift trough is relatively cool, and the potential there for destabilizing subglacial eruptions is low, (2) that extension and over- deepening of interior basins, like the Bentley Subglacial Trench, have taken place beneath the ice sheet in Neogene time, and (3) that dome uplift and the growth of large volcanoes along the Marie Byrd Land coast, together with the subsidence of interior basins, have greatly increased the topographic relief of the rift system in Neogene time. Recent studies suggest that West Antarctic glaciation first appeared during the Oligocene. The implication of this study is that the Oligocene ice sheet originated on a low relief landscape near sea level, adjacent to a much shallower inland sea, and has since evolved in an environment of progressive basin deepening, dome uplift, and volcanism, unlike that of any other ice sheet in the recent past.
DE: 0726 Ice sheets
DE: 8175 Tectonics and landscape evolution
DE: 8178 Tectonics and magmatism
DE: 9310 Antarctica (4207)
SC: Cryosphere [C]
MN: 2007 Fall Meeting